Interposer test structures and methods

ABSTRACT

An embodiment of the disclosure is a structure comprising an interposer. The interposer has a test structure extending along a periphery of the interposer, and at least a portion of the test structure is in a first redistribution element. The first redistribution element is on a first surface of a substrate of the interposer. The test structure is intermediate and electrically coupled to at least two probe pads.

This application is a divisional of U.S. patent application Ser. No.13/198,223, filed on Aug. 4, 2011, entitled “Interposer Test Structuresand Methods,” which claims the benefit of U.S. Provisional ApplicationNo. 61/492,989, filed on Jun. 3, 2011, entitled “Interposer TestStructures and Methods,” which applications are hereby incorporatedherein by reference in their entireties.

BACKGROUND

Since the development of the integrated circuit (IC), the semiconductorindustry has experienced continued rapid growth due to continuousimprovements in the integration density of various electronic components(i.e., transistors, diodes, resistors, capacitors, etc.). For the mostpart, these improvements in integration density have come from repeatedreductions in minimum feature size, which allows more components to beintegrated into a given area.

These integration improvements are essentially two-dimensional (2D) innature, in that the area occupied by the integrated components isessentially on the surface of the semiconductor wafer. The increaseddensity and corresponding decrease in area of the integrated circuit hasgenerally surpassed the ability to bond an integrated circuit chipdirectly onto a substrate. Accordingly, interposers have been used toredistribute ball contact areas from that of the chip to a larger areaof the interposer. Further, interposers have allowed for athree-dimensional (3D) package that includes multiple chips.

Despite the benefits of using an interposer to allow for a reduced sizeof the chip, using an interposer typically has drawbacks. Interposersgenerally introduce new sets of problems that go undetected untilprocessing is completed. Thus, packages having faulty interposers mayundergo processing that is unnecessary because a defect in earlierprocessing rendered the interposers unusable. Some of these problemsgenerally include voids in a through substrate via (TSV, also known as athrough-silicon via or a through semiconductor via), abnormal routing ofa metallization layer after an etch process, a bump cold joint (open orshort circuit), and a crack in an interposer ball.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross section view of an interposer with an integratedcircuit die attached to a first side;

FIGS. 2A through 2H are a first method of forming the interposer withthe integrated circuit die attached to the first side of FIG. 1;

FIGS. 3A through 3F are a second method of forming the interposer withthe integrated circuit die attached to the first side of FIG. 1;

FIG. 4 is a detailed cross section view of a portion of an interposer;

FIGS. 5A and 5B are a layout view of a seal ring pattern of ametallization layer on an interposer;

FIG. 6 is a cross section view of seal rings along a periphery of theinterposer of FIGS. 5A and 5B;

FIG. 7 is a layout view of a seal ring pattern in a metallization layeraccording to an embodiment;

FIG. 8 is a cross section view of the structure of FIG. 7 according tothe embodiment;

FIG. 9 is a layout view of a seal ring pattern in a metallization layeraccording to an embodiment;

FIG. 10 is a cross section view of the structure of FIG. 9 according tothe embodiment;

FIG. 11 is a layout view of a seal ring pattern in metallization layersaccording to an embodiment;

FIGS. 12A through 12C are cross section views of the structure of FIG.11 according to the embodiment;

FIG. 13 is a cross section view of seal rings along a periphery of aninterposer according to an embodiment;

FIG. 14 is a layout view of a seal ring pattern in a metallization layeraccording to an embodiment;

FIG. 15 is a cross section view of the structure of FIG. 14 according tothe embodiment;

FIG. 16 is a layout view of a seal ring pattern in a metallization layeraccording to an embodiment;

FIG. 17 is a cross section view of the structure of FIG. 16 according tothe embodiment;

FIG. 18 is a layout view of a seal ring pattern in metallization layersaccording to an embodiment;

FIGS. 19A through 19C are cross section views of the structure of FIG.18 according to the embodiment;

FIGS. 20 and 21 are general concepts of testing a segment under testaccording to an embodiment;

FIG. 22 is cross section view of a dummy metal via daisy chain in theisolation area of an interposer;

FIG. 23 is a layout view of a seal ring pattern with the metallizationlayers overlaid consecutively and with a probe pad overlaying themetallization layers according to an embodiment;

FIGS. 24 through 26 are cross section views of different configurationsof the via chain structure in FIG. 23 according to various embodiments;

FIGS. 27 and 28 are general concepts of testing a via chain under testaccording to embodiments;

FIG. 29 is a cross section view of a portion of a dummy throughsubstrate via (TSV) daisy chain in an isolation area of an interposeraccording to an embodiment;

FIG. 30 is a plan view of a back side of an interposer according to anembodiment;

FIG. 31 is a cross section view of the interposer of FIG. 30 accordingto the embodiment;

FIG. 32 is a plan view of a back side of an interposer according to anembodiment;

FIG. 33 is a cross section view of the interposer of FIG. 32 with anattached die according to the embodiment;

FIG. 34 is a cross section view of an interposer with an attached dieaccording to an embodiment;

FIGS. 35 through 37 are general concepts of testing a TSV chain undertest according to various embodiments;

FIG. 38 is a front side pattern of an interposer according to anembodiment;

FIG. 39 is an active surface of a die according to an embodiment;

FIG. 40 is a cross section view of a die having an active surface ofFIG. 39 attached to an interposer having a front side pattern of FIG. 38according to an embodiment;

FIG. 41 is a back side pattern of an interposer according to anembodiment;

FIG. 42 is a cross section view of a die having an active surface ofFIG. 39 attached to an interposer having a back side pattern of FIG. 41according to an embodiment;

FIG. 43 is a cross section view of a die having an active surface ofFIG. 39 attached to an interposer according to an embodiment;

FIG. 44 is a cross section view of a die having an active surface ofFIG. 39 attached to an interposer attached to a substrate according toan embodiment;

FIGS. 45 through 48 are general concepts of testing a bump pad and/orbump (BPB) under test according to various embodiments; and

FIG. 49 illustrates a method for forming a die attached to an interposerand for testing structures of the interposer and/or die according to anembodiment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the present embodiments are discussed in detailbelow. It should be appreciated, however, that the present disclosureprovides many applicable inventive concepts that can be embodied in awide variety of specific contexts. The specific embodiments discussedare merely illustrative of specific ways to make and use the disclosedsubject matter, and do not limit the scope of the different embodiments.

Embodiments will be described with respect to a specific context, namelyan interposer and a die attached to an interposer. These embodimentsinclude test structures for testing the reliability of processing forstructures corresponding to the test structures during various steps ofprocessing. While aspects of embodiments are discussed individually, aperson having ordinary skill in the art will readily understand thatembodiments may include many of the individually discussed aspects.Other embodiments may also be applied, however, to other packagingprocesses and packages.

FIG. 1 shows a cross section view of an interposer 10 with an integratedcircuit die 12 attached to a first side of the interposer 10 viaconductive bumps 14. The die 12 includes an interconnect element 16 thatcomprises one or more metallization layers. Die bond pads 18 aremechanically coupled to the die 12 and are electrically coupled todevices in the die 12 via the one or more metallization layers in theinterconnect element 16. The conductive bumps 14 are mechanically andelectrically coupled to the die bond pads 18 and may comprise, forexample, microbumps, pillars, and/or columns having a diameter of about5 microns to about 50 microns.

Interposer bump pads 24 are mechanically coupled to the interposer 10and mechanically and electrically coupled to the conductive bumps 14.The interposer 10 comprises a redistribution layer (RDL) 20 comprisingone or more metallization layer. The RDL 20 allows for a different padconfiguration as well as larger conductive balls 30. The interposer bumppads 24 are electrically coupled to through substrate vias (TSVs, alsoknown as through-silicon vias or through-semiconductor vias) 22 in theinterposer 10 via the one or more metallization layers in the RDL 20.The TSVs 22 extend through a substrate of the interposer 10 from a frontside of the substrate on which the RDL 20 is formed to a back side ofthe substrate. The interposer 10 comprises a passivation structure 26which may include one or more metallization layers, such as a back sideredistribution element. Ball pads 28 are mechanically coupled to theback side of the interposer 10 and are electrically coupled to the TSVs22 directly and/or via the one or more metallization layers in thepassivation structure 26. Conductive balls 30 are mechanically andelectrically coupled to the ball pads 28. The conductive balls 30 maycomprise a diameter of about 60 microns to about 120 microns. Theconductive balls 30 provide external electrical connections from the die12.

FIGS. 2A through 2H illustrate a first method of forming an interposerand a die attached to the interposer, such as the structure illustratedin FIG. 1. It should be appreciated that this order is provided forillustrative purposes, and that other sequences may be used. Referringfirst to FIG. 2A, a substrate 40 of an interposer is shown with TSVs 42formed through a front side of the substrate 40. The substrate 40generally comprises a material similar to the substrate used to form anintegrated circuit die that will be attached to the interposer, such assilicon. While the substrate 40 may be formed of other materials, it isbelieved that using silicon substrates for the interposer may reducestress because the coefficient of thermal expansion (CTE) mismatchbetween the silicon substrates and the silicon typically used for thedies is lower than with substrates formed of different materials.

The TSVs 42 are formed by forming recesses in the substrate 40 by, forexample, etching, milling, laser techniques, a combination thereof,and/or the like. A thin barrier layer is conformally deposited over thefront side of the substrate 40 and in the openings, such as by chemicalvapor deposition (CVD), atomic layer deposition (ALD), physical vapordeposition (PVD), thermal oxidation, a combination thereof, and/or thelike. The barrier layer may comprise a nitride or an oxynitride, such astitanium nitride, titanium oxynitride, tantalum nitride, tantalumoxynitride, tungsten nitride, a combination thereof, and/or the like. Aconductive material is deposited over the thin barrier layer and in theopenings. The conductive material may be formed by an electro-chemicalplating process, CVD, ALD, PVD, a combination thereof, and/or the like.Examples of conductive materials are copper, tungsten, aluminum, silver,gold, a combination thereof, and/or the like. Excess conductive materialand barrier layer is removed from the front side of the substrate 40 by,for example, chemical mechanical polishing. Thus, the TSVs 42 comprise aconductive material and a thin barrier layer between the conductivematerial and the substrate 40.

Front side processing continues in FIG. 2B with the formation of a RDL44. The RDL 44 may comprise any number or combination of metallizationlayers, inter-metal dielectric (IMD) layers, vias, and passivationlayers. The RDL 44 depicted in FIG. 2B comprises three metallizationlayers, such as a first metallization layer (M1) 46, a secondmetallization layer (M2) 48, and a third metallization layer (M3) 50, inIMD layers. Vias formed between metallization layers in the IMD layers.The metallization layers are formed by depositing an IMD layer, etchingthe metallization pattern of the layer in the IMD layer using, forexample, acceptable photolithography techniques, depositing a conductivematerial for the metallization in the IMD, and removing any excessconductive material by, for example, CMP. The photolithography techniquemay include a single damascene process or a dual damascene process,particularly when vias are formed through an IMD to an underlyingmetallization layer.

The IMD layers can be an oxide dielectric, such as a borophosphosilicateglass (BPSG), or other dielectric material. The conductive material ofthe metallization layers may be, for example, copper, nickel, aluminum,copper aluminum, tungsten, titanium, combinations thereof, and/or thelike. The metallization layers may include barrier layers between theconductive material and the IMD material, and other dielectric layers,such as etch stop layers made of, for example, silicon nitride, may beformed between the IMD layers.

After the formation of the top metallization layer, the thirdmetallization layer 50 in FIG. 2B, one or more passivation layers areformed over the metallization layers. The passivation layer(s) may be apolyimide, a BPSG, silicon nitride (SiN), a combination thereof, and/orthe like, and may be formed using a spin-on technique, CVD, ALD, PVD, acombination thereof, and/or the like. Openings 52 are formed through thepassivation layers to expose the top metallization layer, the thirdmetallization layer 50 in FIG. 2B, for the formation of bump pads on thetop metallization layer. The openings 52 may be formed using, forexample, acceptable photolithography and etching techniques.

Referring to FIG. 2C, bump bond pads 54 are formed through the openings52 on the top metallization layer, and conductive bumps 56 are formed onthe bump bond pads 54. The bump bond pads 54 may be formed by depositinga conductive material in the openings 52 and patterning the conductivematerial into the bump bond pads 54. The conductive material maycomprise copper, silver, tin, titanium, tungsten, a combination thereof,and/or the like, and may be deposited by PVD, CVD, ALD, a combinationthereof, and/or the like. The patterning of the bump bond pads 54 may beby acceptable photolithography and etching techniques. The conductivebumps 56 are formed on the bump bond pads 54 by electrochemical plating(ECP), and/or the like, and may comprise copper, tin, nickel, acombination thereof, and/or the like.

In FIG. 2D, integrated circuit dies 58 are attached by the conductivebumps 56, and an underfill material 60 is dispensed between the dies 58and the interposer, for example, the top passivation layer. The dies 58may be known good dies attached using a pick-and-place tool, and theconductive bumps 56 may be reflowed before the underfill material 60 isdispensed. The underfill material 60 may be a liquid epoxy, deformablegel, silicon rubber, a combination thereof, and/or the like dispensedusing acceptable dispensing equipment. In FIG. 2E, after the underfillmaterial 60 is cured, the dies 58 are encapsulated by applying a moldingcompound 62 and using compression molding, for example.

Back side processing of the substrate 40 is depicted as beginning inFIG. 2F. The assembly of FIG. 2E is attached to a carrier substrate 67during the back side processing. The carrier substrate 67 may beattached to the dies 58 and/or the molding compound 62 using anadhesive. Generally, the carrier substrate provides temporary mechanicaland structural support during subsequent processing steps. In thismanner, damage to an interposer is reduced or prevented. The carriersubstrate may comprise, for example, glass, silicon oxide, aluminumoxide, a combination thereof, and/or the like. The adhesive may be anysuitable adhesive, such as ultraviolet (UV) glue, which loses itsadhesive property when exposed to UV lights.

In FIG. 2F, TSVs 42 protrude from the back side of the substrate 40 bythinning the substrate 40. The thinning process may be performed usingan etching process and/or a planarization process, such as a chemicalmechanical polishing (CMP) process. For example, initially a planarizingprocess, such as a CMP, may be performed to initially expose the barrierlayer of the TSVs 42. Thereafter, one or more wet etching processeshaving a high etch-rate selectivity between the material of the barrierlayer and the substrate 40 may be performed, thereby leaving the TSVs 42protruding from the back side of the substrate 40. The etch process mayalso be, for example, a dry etch process. One or more dielectric layers,such as dielectric layer 64 and 66 shown in FIG. 2F, are deposited overthe back side of the substrate 40. The dielectric layers 64 and 66 maybe, for example, silicon oxide, silicon nitride, silicon oxynitride, acombination thereof, and/or the like. The back side is then planarized,for example, by CMP, such that the TSVs 42 are exposed on the back side.

FIG. 2G shows the formation of a passivation layer 68, ball bond pads70, and conductive balls 72. The passivation layer 68 is formed on theback side over the dielectric layers 64 and 66, and may be, for example,a polyimide, BPSG, polybenzoxazole (PBO), a combination thereof, and/orthe like, formed by a spin-on technique, CVD, ALD, a combinationthereof, and/or the like. Openings are formed through the passivationlayer 68 to expose, for example, the TSVs 42, for the formation of ballbond pads 70. The openings may be formed using, for example, acceptablephotolithography and etching techniques. The ball bond pads 70 may beformed by depositing a conductive material, such as a metal, forexample, one or more layers of chrome, a chrome-copper alloy, copper,gold, titanium, titanium tungsten, nickel, combinations thereof, or thelike, in the openings and patterning the conductive material into theball bond pads 70. The conductive material may be deposited by ECPand/or the like, and the patterning may be by acceptablephotolithography and etching techniques. The conductive balls 72 areformed on the ball bond pads 70 by ECP and/or the like, and may comprisecopper, tin, eutectic solder, lead free solder, nickel, a combinationthereof, and/or the like.

It should be noted that FIG. 2G depicts the ball bond pads 70 asdirectly coupled to the TSVs 42; however, one or more metallizationlayers and IMD layers may be formed on the back side of the substrate 40to electrically couple the ball bond pads 70 to the TSVs 42. The backside metallization layers may be formed of any suitable conductivematerial, such as copper, copper alloys, aluminum, silver, gold,combinations thereof, and/or the like, formed by any suitable technique,such as ECP, electroless plating, other deposition methods such assputtering, printing, and CVD, PVD, a combination thereof, and/or thelike.

The assembly is then attached to a dicing frame 74, with the conductiveballs 72 adjoining the dicing frame 74, and the carrier substrate 67 isremoved, as shown in FIG. 2H. The assembly is then diced into individualpackages with an interposer and any number of dies, such as the packageshown in FIG. 1.

FIGS. 3A through 3F illustrate a second method of forming an interposerand a die attached to the interposer, such as the structure illustratedin FIG. 1. It should be appreciated that this order is provided forillustrative purposes, and that other sequences may be used. In thismethod, an assembly is processed through FIG. 2C as previouslydiscussed. The front side of the assembly in FIG. 2C is then attached toa carrier substrate 80 by an adhesive 82, as shown in FIG. 3A. Thecarrier substrate 80 may comprise, for example, glass, silicon oxide,aluminum oxide, a combination thereof, and/or the like. The adhesive 82may be any suitable adhesive, such as UV glue.

Back side processing begins as shown in FIG. 3B. In FIG. 3B, TSVs 42protrude from the back side of the substrate 40 by thinning thesubstrate 40. Causing the TSVs 42 to protrude and the formation of thedielectric layers is similar to or the same as what was discussed withrespect to FIG. 2F. In FIG. 3C, a passivation layer 68, ball bond pads70, and conductive balls 72 are formed. The steps for forming thesecomponents are similar to or the same as what was discussed with respectto FIG. 2G.

In FIG. 3D, the assembly of FIG. 3C is removed from the carriersubstrate 80, for example, by exposing the adhesive 82 to UV radiation,and the assembly is attached to another carrier substrate 84 by anadhesive 86. The back side of the assembly is facing the carriersubstrate 84. The carrier substrate 84 may comprise, for example, glass,silicon oxide, aluminum oxide, a combination thereof, and/or the like.The adhesive 86 may be any suitable adhesive, such as UV glue.

In FIG. 3E, similar to FIG. 2D, integrated circuit dies 58 are attachedto the front side of the assembly, and an underfill material 60 isdispensed between the dies 58 and the interposer, for example, the toppassivation layer. In FIG. 3F, the carrier substrate 84 is removed fromthe assembly, for example, by exposing the adhesive 86 to UV radiation.The assembly is then attached to a dicing frame 74 with the back sidefacing away from the dicing frame 74, for example, with the conductiveballs 72 facing away from the dicing frame 74. The assembly is thendiced into individual packages with an interposer and any number ofdies, such as the package shown in FIG. 1.

FIG. 4 is a detailed cross section view of a portion of an interposer.The interposer comprises a substrate 90 having a TSV 92. The substrateis, for example, a silicon substrate. The TSV 92 extends from a frontside surface to a back side surface of the substrate 90 by a depth 96.The TSV 92 has a width 94, which may also be a diameter. The depth 96may be between approximately 50 micrometers to approximately 200micrometers, and the width 94 may be between about 3 micrometers toabout 15 micrometers. The TSV 92 may have an aspect ratio that isbetween about 6 to about 18.

The interposer further comprises, formed on the front side surface, afirst metallization layer 98, a second metallization layer 100, and athird metallization layer 102 formed in a first IMD layer 104, a secondIMD layer 106, and a third IMD layer 108, respectively. A first via 110electrically couples a portion of the first metallization layer 98 to aportion of the second metallization layer 100, and a second via 112electrically couples a portion of the second metallization layer 100 toa portion of the third metallization layer 102.

A first passivation layer 114 is formed over the third metallizationlayer 102 and the third IMD layer 108 and is patterned to expose aportion of the third metallization layer 102. A bond pad 116 is formedon the exposed portion of the third metallization layer 102 and includesa flange portion over the first passivation layer 114. A secondpassivation layer 118 is formed over the first passivation layer 114 andthe flange portion of the bond pad 116. The bond pad 116 is exposedthrough the second passivation layer 118. A conductive bump 120 is onthe bond pad 116 and has a diameter of, for example, approximately 25micrometers.

The interposer also comprises, formed on the back side surface, a backside metallization layer 122. A back side passivation layer 124 isformed over the back side metallization layer 122 and is patterned toexpose a portion of the back side metallization layer 122. A conductiveball 126 is formed on the exposed portion of the back side metallizationlayer 122 and has a diameter of, for example, about 100 micrometers.

FIGS. 5A and 5B illustrate a layout view of a seal ring pattern 130 of ametallization layer(s) on an interposer. The seal ring pattern 130 maybe for one metallization layer, all metallization layers, or anycombination of metallization layers formed, for example, on a front sideof the interposer. FIG. 5A depicts an edge 132 of the interposer andidentifies a view 134 of a corner that is expanded in FIG. 5B. FIG. 5Billustrates the pattern of an inner seal ring pattern 136 and an outerseal ring pattern 138. Each of the inner seal ring pattern 136 and theouter seal ring pattern 138 extends along the edge 132 some distanceinterior to the edge 132 except extends at forty-five degrees from theedge 132 near a corner. A corner pattern 140 extends into the cornerexterior to where the outer seal ring pattern 138 extends at theforty-five degree angle, and the corner pattern 140 is coupled to theouter seal ring pattern 138. The corner pattern 140 may also be referredto as a corner stress relief (CSR) area.

FIG. 6 illustrates a cross section view of seal rings along a peripheryof an interposer. The interposer includes a substrate 150 with IMDlayers 152 formed on a front side surface of the substrate 150. In theIMD layers 152 are a first metallization layer 154, a secondmetallization layer 156, and a third metallization layer 158 formed of,for example, copper, although any of the other materials discussedpreviously may be used. Each of the metallization layers 154, 156, and158 includes a portion in an outer seal ring 162 and an inner seal ring164. The portions of the metallization layers 154, 156, and 158 in theouter seal ring 162 include the outer seal ring pattern 138 and thecorner pattern 140 shown in FIGS. 5A and 5B. Similarly, the portions ofthe metallization layers 154, 156, and 158 in the inner seal ring 164include the inner seal ring pattern 136 shown in FIGS. 5A and 5B.Discrete vias 166 and via bars 168 electrically couple the metallizationlayers 154, 156, and 158 together. Via bars 168 generally extend alongthe edge 132 similar to the outer seal ring pattern 138 or the innerseal ring pattern 136.

A first passivation layer 170 is formed over the top IMD layer of theIMD layers 152 and the third metallization layer 158. The portion of thethird metallization layer 158 in the outer seal ring 162 is exposed byan opening, and a pad 172 is formed in the opening electrically coupledto the portion of the third metallization layer 158 in the outer sealring 162. The pad 172 comprises, for example, aluminum or copperaluminum, although other materials previously discussed may be used. Aflange portion of the pad 172 is over the first passivation layer 170. Asecond passivation layer 174 is over the first passivation layer 170 andpart of the flange portion of the pad 172. The pad 172 is exposedthrough the second passivation layer 174. It should be noted that insome structures, the pad 172 may not be present, and various openingsthrough the first passivation layer 170 and the second passivation layer174 may or may not be present.

The structures in the interposer may have various dimensions, which mayfurther be modified depending on the technology node used. Dimensionsfor the interposer are exemplary for a 65 nanometer technology node anddo not limit the scope of embodiments. FIG. 6 further illustrates anisolation area 176 interior to the interposer from the inner seal ring164. The isolation area may have a width 180 of, for example, about 10micrometers from the inner edge of the inner seal ring 164 extendinginwardly towards the center of the interposer. The inner seal ring 164may have a width 182 of, for example, about 3.5 micrometers. A distance184 between an outer edge of the inner seal ring 164 and an inner edgeof the outer seal ring 162 may be, for example, about 2.5 micrometers.The outer seal ring 162 may have a width 186 of, for example, about 2micrometers. A distance 188 from the outer edge of the outer seal ring162 to the edge 132 of the interposer may be, for example, about 2micrometers. The pad 172 may have a width 190 between sidewalls of thefirst passivation layer 170 of, for example, about 2 micrometers. Aflange portion of the pad 172 may have a width 192 adjacent the edge 132of, for example, about 1 micrometer, and an opposite width 194 of, forexample, about 2 micrometers.

FIG. 7 illustrates a view 134 a of a metallization layer, which is amodification of the seal ring pattern of FIGS. 5A and 5B. A probe pad200 is formed in the corner and is connected by a line 202 to the innerseal ring pattern 136. The outer seal ring pattern 138 is discontinuouswhere the line 202 intersects the outer seal ring pattern 138. Similarprobe pads and lines may be formed in each corner.

FIG. 8 illustrates a cross section view of the structure of FIG. 7. Itshould be noted that FIG. 8 is a simplified view because the connectionsof FIG. 7 generally do not align in a single cross section plane. FIG. 8shows the structure before processing is completed, such as afterforming an appropriate metallization layer and/or IMD layer as discussedwith regard to FIG. 2B but before the formation of an overlying IMDlayer or passivation layer. FIG. 8 depicts a segment under test 204,which is, for example, a portion of one of the metallization layers 154,156, and 158 in the inner seal ring 164 of FIG. 6 and a segment of theinner seal ring pattern 136 in FIG. 7, with a combination probe pad 200and connection 202 at opposing ends of the segment under test 204. Thesegment under test 204 may be in any of the metallization layers, andtherefore, may be over only the substrate 150 or over any of the IMDlayers 152 (depicted as “150/152”). The segment under test 204 iselectrically isolated from a metallization layer that may underlie thesegment under test 204.

After forming the particular metallization layer in which the segmentunder test 204 is formed and before forming an immediately overlying IMDlayer or passivation layer, the segment under test 204 of the inner sealring pattern 136 is tested by probing the probe pads 200 at respectiveends of the segment. By applying a signal at one probe pad 200, it canbe determined whether the segment under test 204 has a void ordiscontinuity in the metallization of the segment by sensing a signal atanother probe pad 200 at an opposite end of the segment under test 204.Typically, the segment under test 204 will be electrically isolated fromor independent of other electrical paths. For example, the inner sealring pattern 136 in which the segment under test 204 is formed typicallywill not form an enclosed loop because doing so will allow the testsignal to travel around the loop between the probe pads 200 when thesegment under test 204 is open, e.g., has a void or discontinuity.Further, the segment under test 204 generally will not be coupled tounderlying metallization to avoid an alternate path for the test signal.After testing, a subsequent IMD layer and/or passivation layer may beformed. If a metallization layer is formed over the metallization layerin which the segment under test 204 is formed, the overlyingmetallization layer may be electrically coupled to the segment undertest 204 because the testing occurred before the formation of theoverlying metallization layer.

FIG. 9 illustrates another view 134 b with a metallization layeroverlaid with a probe pad 210. FIG. 9 is a modification of the seal ringpattern of FIGS. 5A and 5B. The probe pad 210 is formed, for example,contemporaneously with bump bond pads, such as bump bond pads 54 in FIG.2C. The probe pad 210 is formed in the corner and is electricallycoupled through an interconnect structure (not shown in FIG. 9) and aline 202 to the inner seal ring pattern 136. The outer seal ring pattern138 is discontinuous where the line 202 intersects the outer seal ringpattern 138. Similar probe pads, interconnect structures, and lines maybe formed in each corner.

FIG. 10 illustrates a cross section view of the structure of FIG. 9. Itshould be noted that FIG. 10 is a simplified view because theconnections of FIG. 9 generally do not align in a single cross sectionplane. FIG. 10 shows the structure after bump bond pads are formed, suchas after forming bump bond pads 54 as discussed with regard to FIG. 2C,but before subsequent processing such as discussed with regard to FIG.2D or 3A. FIG. 10 depicts a segment under test 212, which is, in thisexample, a portion of the first metallization layer 154 in the innerseal ring 164 of FIG. 6 and a segment of the inner seal ring pattern 136in FIG. 9. At each of opposing ends of the segment under test 212 is aninterconnect structure electrically coupling the probe pad 210 to thesegment under test 212. Each of the interconnect structures comprises alanding portion 214 of the third metallization layer 158, a landingportion 216 of the second metallization layer 156, a via 218 connectingthe landing portions 214 and 216, and a via 220 connecting the landingportion 216 to a combination of a landing portion and line 202 of thefirst metallization layer 154.

Although the segment under test 212 is depicted in FIG. 10 in the firstmetallization layer 154, the segment under test 212 may be in any of themetallization layers. A person having ordinary skill in the art willreadily understand the modifications to the interconnect structures andmetallization patterns to form these different structures. It is worthnoting that although no portion of another metallization layer (besideswhat is shown in the interconnect structures) is depicted in the crosssection of FIG. 10, portions of other metallization layers may overlieor underlie the segment under test 212. The segment under test 212 istypically electrically isolated from portions of a metallization layerthat may underlie or overlie the segment under test 212, with theexception of the portions of the interconnect structures.

After completing processing through the formation of bump bond pads,such as bump bond pads 54 as discussed with regard to FIG. 2C, butbefore subsequent processing such as discussed with regard to FIG. 2D or3A, the segment under test 212 of the inner seal ring pattern 136 istested by probing the probe pads 210 at respective ends of the segment.By applying a signal at one probe pad 210, it can be determined whetherthe segment under test 212 has a void or discontinuity in themetallization of the segment by sensing a signal at another probe pad210 at an opposite end of the segment under test 212. Typically, thesegment under test 212 will be electrically isolated from or independentof other electrical paths. For example, similar to above, the inner sealring pattern 136, in which the segment under test 212 is formed,typically will not form an enclosed loop, and the segment under test 212generally will not be coupled to underlying metallization to avoid analternate path for the test signal.

FIG. 11 illustrates a further view 134 c with the metallization layersoverlaid consecutively and with probe pads 230, 232, and 234 overlayingthe metallization layers. The view 134 c is a modification of the sealring pattern of FIGS. 5A and 5B. The probe pads 230, 232, and 234 areformed, for example, contemporaneously with bump bond pads, such as bumpbond pads 54 in FIG. 2C. The probe pads 230, 232, and 234 are formed inthe corner and are electrically coupled through an interconnectstructure (not shown in FIG. 11) and a respective line 236, 238, and 240to the inner seal ring pattern 136 of a respective metallization layer154, 156, and 158. The outer seal ring pattern 138 is discontinuouswhere the lines 236, 238, and 240 intersect the outer seal ring pattern138. Similar probe pads, interconnect structures, and lines may beformed in each corner.

FIGS. 12A to 12C illustrate cross section views of the structure of FIG.11. It should be noted that FIGS. 12A to 12C are simplified viewsbecause the connections of FIG. 11 generally do not align in a singlecross section plane. FIGS. 12A to 12C show the structure after bump bondpads are formed, such as after forming bump bond pads 54 as discussedwith regard to FIG. 2C, but before subsequent processing such asdiscussed with regard to FIG. 2D or 3A.

FIG. 12A depicts a segment under test 250, which is, in this example, aportion of the first metallization layer 154 in the inner seal ring 164of FIG. 6 and a segment of the inner seal ring pattern 136 in FIG. 11.At each of opposing ends of the segment under test 250 is aninterconnect structure electrically coupling the probe pad 234 to thesegment under test 250. Each of the interconnect structures comprises alanding portion 260 of the third metallization layer 158, a landingportion 262 of the second metallization layer 156, a via 264 connectingthe landing portions 260 and 262, and a via 266 connecting the landingportion 262 to a combination of a landing portion and line 240 of thefirst metallization layer 154.

FIG. 12B depicts a segment under test 252, which is, in this example, aportion of the second metallization layer 156 in the inner seal ring 164of FIG. 6 and a segment of the inner seal ring pattern 136 in FIG. 11.At each of opposing ends of the segment under test 252 is aninterconnect structure electrically coupling the probe pad 232 to thesegment under test 252. Each of the interconnect structures comprises alanding portion 268 of the third metallization layer 158 and a via 270connecting the landing portion 268 to a combination of a landing portionand line 238 of the second metallization layer 156.

FIG. 12C depicts a segment under test 254, which is, in this example, aportion of the third metallization layer 158 in the inner seal ring 164of FIG. 6 and a segment of the inner seal ring pattern 136 in FIG. 11.At each of opposing ends of the segment under test 254 is a structureelectrically coupling the probe pad 230 to the segment under test 254.Each of the structures comprises a combination of a landing portion andline 236 of the third metallization layer 158.

Although the segments under test 250, 252, and 254 are depictedindividually in FIGS. 12A through 12C, the segments under test 250, 252,and 254 are generally overlaid, although other configurations may beused. A person having ordinary skill in the art will readily understandthe modifications to the interconnect structures and metallizationpatterns to form these different structures. As with previous figures,in FIGS. 12A through 12B, portions of other metallization layers mayoverlie or underlie the segments under test 250, 252, and 254. Thesegments under test 250, 252, and 254 are typically electricallyisolated from portions of a metallization layer that may underlie oroverlie the segments under test 250, 252, and 254, with the exception ofthe portions of the interconnect structures.

After completing processing through the formation of bump bond pads,such as bump bond pads 54 as discussed with regard to FIG. 2C, butbefore subsequent processing such as discussed with regard to FIG. 2D or3A, the segments under test 250, 252, and 254 of the inner seal ringpattern 136 are tested by probing the probe pads 230, 232, and 234 atrespective ends of the respective segment. Each of the segments undertest 250, 252, and 254 may be tested as discussed with respect to thestructures shown in FIGS. 9 and 10. Typically, the segments under test250, 252, and 254 will be electrically isolated from or independent ofother electrical paths. For example, similar to above, the inner sealring pattern 136, in which each of the segments under test 250, 252, and254 is formed, typically will not form an enclosed loop, and thesegments under test 250, 252, and 254 generally will not be coupled tounderlying or overlying metallization to avoid an alternate path for thetest signal.

FIG. 13 illustrates another cross section view of seal rings along aperiphery of an interposer similar to FIG. 6. In FIG. 13, the interposerincludes a line 280, 282, and 284 between the inner seal ring 164 andthe outer seal ring 162 in each of the metallization layers 154, 156,and 158, respectively. The lines 280, 282, and 284 extend similarlyalong the periphery of the interposer as the seal rings 162 and 164.Further, the lines 280, 282, and 284 have a minimum design rule width inthis example. In this example with a 65 nanometer technology node, theminimum design rule width is about 0.324 micrometers, and thus, each ofthe lines 280, 282, and 284 has a width of about 0.324 micrometers.

FIG. 14 illustrates another view 134 d of a metallization layer, whichis a modification of the seal ring pattern of FIGS. 5A and 5B. In FIG.14, a line pattern 290 is between the inner seal ring pattern 136 andthe outer seal ring pattern 138. In the view 134 d of FIG. 14, a probepad 200 is formed in the corner and is connected by a line 292 to theline pattern 290. The outer seal ring pattern 138 is discontinuous wherethe line 292 intersects the outer seal ring pattern 138. Similar probepads and lines may be formed in each corner.

FIG. 15 illustrates a cross section view of the structure of FIG. 14.FIG. 15 depicts a segment under test 294, which is, for example, one oflines 280, 282, and 284, which is a portion of one of the metallizationlayers 154, 156, and 158, respectively, of FIG. 13 and a segment of theline pattern 290 in FIG. 14. The segment under test 294 has acombination probe pad 200 and connection 292 at opposing ends of thesegment under test 294. The segment under test 294 may be in any of themetallization layers, and therefore, may be over only the substrate 150or over any of the IMD layers 152 (depicted as “150/152”). The segmentunder test 294 is electrically isolated or independent and may be testedin the same manner as discussed for the segment under test 204 in FIGS.7 and 8.

FIG. 16 illustrates another view 134 e with a metallization layeroverlaid with a probe pad 210. FIG. 16 is a modification of the sealring pattern of FIGS. 5A and 5B. In FIG. 16, the view 134 e includes aline pattern 290 between the inner seal ring pattern 136 and the outerseal ring pattern 138. In the view 134 e of FIG. 16, a metallizationlayer is shown overlaid with a probe pad 210. The probe pad 210 isformed in the corner and is electrically coupled through an interconnectstructure (not shown in FIG. 16) and a line 292 to the line pattern 290.The outer seal ring pattern 138 is discontinuous where the line 292intersects the outer seal ring pattern 138. Similar probe pads,interconnect structures, and lines may be formed in each corner.

FIG. 17 illustrates a cross section view of the structure of FIG. 16.FIG. 17 depicts a segment under test 300, which is a portion of thefirst metallization layer 154 of FIG. 13 and a segment of the linepattern 290 in FIG. 16. At each of opposing ends of the segment undertest 300 is an interconnect structure electrically coupling the probepad 210 to the segment under test 300. Each of the interconnectstructures comprises a landing portion 302 of the third metallizationlayer 158, a landing portion 304 of the second metallization layer 156,a via 306 connecting the landing portions 302 and 304, and a via 308connecting the landing portion 304 to a combination of a landing portionand line 292 of the first metallization layer 154.

The segment under test 300 may be, for example, any of lines 280, 282,and 284, which is a portion of one of the metallization layers 154, 156,and 158, respectively, of FIG. 13. A person having ordinary skill in theart will readily understand the modifications to the interconnectstructures and metallization patterns to form these differentstructures. It is worth noting that portions of other metallizationlayers may overlie or underlie the segment under test 300. The segmentunder test 300 is typically electrically isolated from portions of ametallization layer that may underlie or overlie the segment under test300, with the exception of the portions of the interconnect structures.The segment under test 300 may be tested in the same manner as discussedfor the segment under test 212 in FIGS. 9 and 10.

FIG. 18 illustrates a further view 134 f with the metallization layersoverlaid consecutively and with probe pads 230, 232, and 234 overlayingthe metallization layers. The view 134 f is a modification of the sealring pattern of FIGS. 5A and 5B. In FIG. 18, the view 134 f includes aline pattern 290 between the inner seal ring pattern 136 and the outerseal ring pattern 138. The probe pads 230, 232, and 234 are formed inthe corner and are electrically coupled through an interconnectstructure (not shown in FIG. 18) and a respective line 310, 312, and 314to the line pattern 290 of a respectively metallization layer 154, 156,and 158. The outer seal ring pattern 138 is discontinuous where thelines 310, 312, and 314 intersect the outer seal ring pattern 138.Similar probe pads, interconnect structures, and lines may be formed ineach corner.

FIGS. 19A to 19C illustrate cross section views of the structure of FIG.18. FIG. 19A depicts a segment under test 320, which is, in thisexample, a portion of the line 280 in the first metallization layer 154of FIG. 13 and a segment of the line pattern 290 in FIG. 18. At each ofopposing ends of the segment under test 320 is an interconnect structureelectrically coupling the probe pad 234 to the segment under test 320.Each of the interconnect structures comprises a landing portion 330 ofthe third metallization layer 158, a landing portion 332 of the secondmetallization layer 156, a via 334 connecting the landing portions 330and 332, and a via 336 connecting the landing portion 332 to acombination of a landing portion and line 314 of the first metallizationlayer 154.

FIG. 19B depicts a segment under test 322, which is, in this example, aportion of the line 282 in the second metallization layer 156 of FIG. 13and a segment of the line pattern 290 in FIG. 18. At each of opposingends of the segment under test 322 is an interconnect structureelectrically coupling the probe pad 232 to the segment under test 322.Each of the interconnect structures comprises a landing portion 338 ofthe third metallization layer 158 and a via 340 connecting the landingportion 338 to a combination of a landing portion and line 312 of thesecond metallization layer 156.

FIG. 19C depicts a segment under test 324, which is, in this example, aportion of the line 284 in the third metallization layer 158 of FIG. 13and a segment of the line pattern 290 in FIG. 18. At each of opposingends of the segment under test 324 is a structure electrically couplingthe probe pad 230 to the segment under test 324. Each of the structurescomprises a combination of a landing portion and line 310 of the thirdmetallization layer 158.

Although the segments under test 320, 322, and 324 are depictedindividually in FIGS. 19A through 19C, the segments under test 320, 322,and 324 are generally overlaid, although other configurations may beused. A person having ordinary skill in the art will readily understandthe modifications to the interconnect structures and metallizationpatterns to form these different structures. As with previous figures,portions of other metallization layers may overlie or underlie thesegments under test 320, 322, and 324. The segments under test 320, 322,and 324 are typically electrically isolated from portions of ametallization layer that may underlie or overlie the segments under test320, 322, and 324, with the exception of the portions of theinterconnect structures. Further, the line pattern 290, in which each ofthe segments under test 320, 322, and 324 is formed, typically will notform an enclosed loop to avoid an alternate path for the test signal.Each of the segments under test 320, 322, and 324 may be tested asdiscussed with respect to the structures shown in FIGS. 11 and 12Athrough 12C.

FIGS. 20 and 21 illustrate general concepts of testing a segment undertest. In FIG. 20, probe pads 200 are probed to apply and sense a testsignal through a segment under test 350. The probe pads 200 are alsoshown in FIGS. 8 and 15, and the segment under test may be the segmentunder test 204 or 294 in FIG. 8 or 15, respectively. In FIG. 21, probepads 352 are electrically coupled, for example, through interconnectstructures to a segment under test 354. The probe pads 352 are probed toapply and sense a test signal through the segment under test 354. Theprobe pads 352 may be the probe pads 210, 230, 232, and 234, and thesegment under 354 may be the segment under test 212, 250, 252, 254, 300,320, 322, and 324, as shown in FIGS. 10, 12A, 12B, 12C, 17, 19A, 19B,and 19C.

FIG. 22 illustrates cross section view of a dummy metal via daisy chainin the isolation area of an interposer. FIG. 22 is similar to FIG. 6except for a dummy metal via daisy chain (“via chain”) structure 400 inthe isolation area 176. The via chain structure 400 includes a firstportion 402 of the first metallization layer 154, a second portion 404of the second metallization layer 156, vias 410 connecting the firstportion 402 and the second portion 404, a third portion 406 of the thirdmetallization layer 158, vias 412 connecting the second portion 404 andthe third portion 406, and a probe pad 408 exposed through the secondpassivation layer 174 and connected to the third portion 406. In thisexample, the metallization layers 154, 156, and 158 are copper, and theprobe pad 408 is aluminum or copper aluminum, although other materialspreviously discussed may be used for these components.

FIG. 23 illustrates a further view 134 g with the metallization layersoverlaid consecutively and with the probe pad 408 overlaying themetallization layers. The view 134 g is a modification of FIGS. 5A and5B. Via chain pattern 414 of the combined metallization layersillustrates the area in which the via chain structure 400 is formed. Thevia chain pattern 414 may extend along a periphery of the interposer,such as along each edge of the interposer, and generally is interior tothe inner seal ring pattern 136 in the isolation area 176. The probe pad408 is electrically coupled to the via chain pattern 414. Similar probepads and lines may be formed in each corner.

FIGS. 24 through 26 depict cross section views of differentconfigurations of the via chain structure 400. FIGS. 24 through 26 showthe structure after bump bond pads are formed, such as after formingbump bond pads 54 as discussed with regard to FIG. 2C, but beforesubsequent processing such as discussed with regard to FIG. 2D or 3A.

FIG. 24 shows a via chain under test 420 between probe pads 408. The viachain under test 420 comprises landing portions 422 of the firstmetallization layer 154, landing portions 424 of the secondmetallization layer 156, vias 428 connecting respective landing portions422 and 424, landing portions 426 of the third metallization layer 158,and vias 430 connecting respective landing portions 424 and 426. In thisconfiguration, the landing portions and vias are stair-stepped throughthe various IMD layers 152. For example, the landing portions do notcompletely vertically align in the IMD layer 152 although landingportions in adjacent metallization layers partially overlap, and thevias do not vertically align. This configuration also shows three fullcycles of the via chain under test 420 through the metallization and IMDlayers. Other configurations may have different numbers of cycles, andin even further configurations, each cycle may not extend through eachof the layers.

FIG. 25 shows a via chain under test 440 between probe pads 408. The viachain under test 440 comprises landing portions 442 of the firstmetallization layer 154, landing portions 444 of the secondmetallization layer 156, vias 448 connecting respective landing portions442 and 444, landing portions 446 of the third metallization layer 158,and vias 450 connecting respective landing portions 444 and 446. In thisconfiguration, the landing portions and vias are in a “ladder” or“elevator” configuration through the various IMD layers 152. Forexample, landing portions vertically align in the IMD layer 152, andvias vertically align. This configuration also shows three full cyclesof the via chain under test 440 through the metallization and IMDlayers. Other configurations may have different numbers of cycles, andin even further configurations, each cycle may not extend through eachof the layers.

FIG. 26 shows a via chain under test 460 between probe pads 408. The viachain under test 460 comprises a line 462 of the first metallizationlayer 154, landing portions 464 of the second metallization layer 156,vias 468 connecting the line 462 to landing portion 464, landingportions 466 of the third metallization layer 158, and vias 470connecting respective landing portions 464 and 466. In thisconfiguration, the landing portions and vias are in a “ladder” or“elevator” configuration through the various IMD layers 152, as in FIG.25. The line 462 may be an ultra long test line, such as approximately10 millimeters, to test a front side RDL chain yield. The line 462 maybe on any metallization layer.

The via chain under test 420, 440, or 460 is typically electricallyisolated from other portions of a metallization layer that are notdepicted in the figures. Thus, the via chain under test 420, 440, or 460may be independent during testing.

After completing processing through the formation of bump bond pads,such as bump bond pads 54 as discussed with regard to FIG. 2C, butbefore subsequent processing such as discussed with regard to FIG. 2D or3A, the via chain under test 420, 440, or 460 of the via chain structure400 is tested by probing the probe pads 408 at respective ends of thevia chain. FIGS. 27 and 28 generally show the tested structure. In FIG.27, probe pads 408 are probed to apply and sense a test signal through avia chain under test 420/440. FIG. 27 shows the cycles of vias andlanding portions in the via chain structure 400. In FIG. 28, probe pads408 are electrically coupled to the via chain under test 460 thatcomprises vias and a line, as shown in FIG. 26. The probe pads 408 areprobed to apply and sense a test signal through the via chain under test460. By applying a signal at one probe pad 408, it can be determinedwhether the via chain under test 420, 440, or 460 has a void ordiscontinuity in a via or a metallization of the via chain structure 400by sensing a signal at another probe pad 408 at an opposite end of thevia chain under test 420, 440, or 460. Typically, the via chain undertest 420, 440, or 460 will be electrically isolated from or independentof other electrical paths. For example, the via chain pattern 414, inwhich the via chain under test 420, 440, or 460 is formed, typicallywill not form an enclosed loop, and the via chain under test 420, 440,or 460 generally will not be coupled to other portions of ametallization layer to avoid an alternate path for the test signal.

FIG. 29 illustrates a cross section view of a portion of a dummy TSVdaisy chain in the isolation area 176 of an interposer. FIG. 29 issimilar to FIG. 6 except for a dummy TSV daisy chain (“TSV chain”)structure 490 in the isolation area 176. The TSV chain structure 490includes a back side metallization portion 506 in a back side dielectriclayer 508, a TSV 504 through the substrate 150 and connected to the backside metallization portion 506, a first portion 492 of the firstmetallization layer 154 connected to the TSV 504, a second portion 494of the second metallization layer 156, vias 500 connecting the firstportion 492 and the second portion 494, a third portion 496 of the thirdmetallization layer 158, vias 502 connecting the second portion 494 andthe third portion 496, and a pad 498 under the second passivation layer174 and connected to the third portion 496.

In this example, the TSV 504 has a width 510 of approximately 12micrometers. A first TSV portion 512 of the TSV width 510 is in theisolation area 176 and is approximately 8 micrometers. A second TSVportion 514 of the TSV width 510 is outside of the isolation area 176and is approximately 4 micrometers. Further in this example, the firstportion 492 of the first metallization layer 154 has a width 516 ofapproximately 14 micrometers and an overhang portion 518 extending outfrom the TSV 504 of approximately 1 micrometer. Further, the pad 498 hasa width 520 between sidewalls of the first passivation layer 170 ofapproximately 2 micrometers.

FIG. 30 depicts a plan view of a back side 540 of an interposer with afront side pattern 542 shown in phantom. The back side 540 includes aback side chain pattern 544 and probe pads 546 in the back sidemetallization 506 of the interposer. The probe pads 546 are formed inthe corners of the interposer. The back side chain pattern 544 is aportion of the TSV chain structure 490 shown in FIG. 29. Two of theprobe pads 546 are electrically coupled to an independent TSV chainunder test.

FIG. 31 illustrates a cross section view of the structure of FIG. 30. Itshould be noted that FIG. 31 shows a die and bumps in phantom as areference point because a die and bumps typically do not intersect thedepicted plane of the isolation area in which the TSV chain structure490 is formed. Further, the structures depicted may not be in a samecross section plane. FIG. 31 shows the structure before processing iscompleted, such as after back side thinning and back side metallizationdeposition but before formation of balls, as discussed with regard toFIGS. 2F and 3B.

FIG. 31 depicts a TSV chain under test 550, which includes, for example,portions 492, 494, and 496 of the metallization layers 154, 156, and158, respectively, on the front side of the interposer, portions of theback side metallization layer 506, and TSVs 504 of FIG. 29, with probepads 546 at opposing ends of the TSV chain under test 550. As shown inFIG. 31, the TSVs 504 are electrically coupled together in a daisy chainthrough the portions 496 of the third metallization layer 158 on thefront side and through the portions of the back side metallization layer506. The TSVs 504 in the TSV chain under test 550 may be electricallycoupled by any of the metallization layers, such as directly coupled bythe portions 492 of the first metallization layer 154 and directlycoupled by the portions of the back side metallization layer 506. Othercombinations of metallization layers to form a daisy chain, or serialelectrical coupling, are within the skill of a person having ordinaryskill in the art and are contemplated within the scope of otherembodiments. The TSV chain under test 550 is electrically isolated fromother portions of metallization layers.

After forming the back side metallization layer and corresponding IMDlayer or passivation layer but before the formation of conductive balls,such as conductive balls 72 in FIGS. 2G and 3C, the TSV chain under test550 in the isolation area 176 is tested by probing the probe pads 546 atrespective ends of the chain. By applying a signal at one probe pad 546,it can be determined whether the TSV chain under test 550 has a void ordiscontinuity in the chain by sensing a signal at another probe pad 546at an opposite end of the TSV chain under test 550. Typically, the TSVchain under test 550 will be electrically isolated from or independentof other electrical paths. For example, various metallization layers,such as the back side chain portion 544, in which the TSV chain undertest 550 is formed, typically will not form an enclosed loop becausedoing so will allow the test signal to travel around the loop betweenthe probe pads when the TSV chain under test 550 is open, e.g., has avoid or discontinuity. After testing, a subsequent IMD layer and/orpassivation layer may be formed. If a metallization layer is formed overthe back side metallization layer of which the TSV chain under test 204is a part, the overlying back side metallization layer may beelectrically coupled to the TSV chain under test 550 because the testingoccurred before the formation of the overlying metallization layer.

FIG. 32 depicts a plan view of a back side 560 of an interposer with afront side pattern 542 shown in phantom. The back side 560 includesprobe pads 562 in the back side metallization 506 of the interposer. Theprobe pads 546 are formed along a periphery of the interposer in theisolation area 176. Also present in the back side metallization 506, butnot specifically shown in FIG. 32, are interconnects between TSVs 504 ofa TSV chain structure, similar to the TSV chain structure 490 shown inFIG. 29 but not generally in the isolation area 176. Two of the probepads 562 in the isolation area 176 are electrically coupled to anindependent TSV chain under test.

FIG. 33 illustrates a cross section view of the structure of FIG. 32.The structures depicted in FIG. 33 are shown in a cross section planefor simplicity of illustration and may not necessarily be in a samecross section plane. FIG. 33 shows the structure before processing iscompleted, such as after back side thinning and back side metallizationdeposition but before formation of balls, as discussed with regard toFIGS. 2F and 3B. FIG. 33 shows a die 572 connected to an interposer toform a TSV chain under test 570. The TSV chain under test 570 includes,for example similar to FIG. 31, portions 492, 494, and 496 of themetallization layers 154, 156, and 158, respectively, on the front sideof the interposer, a portion of the back side metallization layer 506,TSVs 504, and probe pads 546 at opposing ends of the TSV chain undertest 570. The TSV chain under test 570 further includes dummy bumpstructures 574, which include corresponding bump pads of the interposerand of the die 572, and portions 576 of a metallization layer of the die572. Active bump structures 578 are also illustrated for reference.

As shown in FIG. 33, the TSVs 504 are electrically coupled together in adaisy chain through the portions 576 of the metallization layer of thedie 572 and through the portions of the back side metallization layer506. The TSVs 504 in the TSV chain under test 570 may be electricallycoupled by any of the metallization layers of the die 572. Othercombinations of metallization layers to form a daisy chain are withinthe skill of a person having ordinary skill in the art and arecontemplated within the scope of other embodiments. The TSV chain undertest 570 is electrically isolated from other portions of metallizationlayers, such as active portions. The testing of the TSV chain under test570 may be performed the same as or similar to the testing of the TSVchain under test 550 previously discussed with respect to FIG. 31.

FIG. 34 is a modification of FIG. 33. Instead of forming probing pads546, for example, dummy ball structures 582, which include correspondingunderlying bond pads, are formed for testing the TSV chain under test580. An active ball structure 584 is also shown for reference. Thetesting of the TSV chain under test 580 may be performed after theformation of bond pads and/or balls, such as after the formation of ballbond pads 70 and/or conductive balls 72 in FIG. 2G or FIG. 3C. Similarto probing probe pads 546 in FIGS. 31 and 33, the dummy ball structures582 may be probed to apply and sense a test signal.

FIGS. 35, 36, and 37 illustrate general concepts of testing a TSV chainunder test. In FIG. 35, probe pads 546 are probed to apply and sense atest signal through a TSV chain under test 550, as also shown in FIG.31. The TSVs 504 are daisy chained together by various metallizationlayers. In FIG. 36, probe pads 546 are probed to apply and sense a testsignal through a TSV chain under test 570, as also shown in FIG. 33. TheTSVs 504 are daisy chained together by various metallization layers ofthe interposer, bump structures, and metallization layer(s) of the die.In FIG. 37, dummy ball structures 582 are probed to apply and sense atest signal through a TSV chain under test 580, as also shown in FIG.34. The TSVs 504 are daisy chained together by various metallizationlayers of the interposer, bump structures, and metallization layer(s) ofthe die.

FIGS. 38 and 39 illustrate patterns for bumps under test. FIG. 38 showsa front side pattern 600 of an interposer. The front side pattern 600includes probe pads 602 along a periphery of the front side pattern 600,a die-attach area 604, bump pads and/or bumps (“BPBs”) under test 606,and sense BPBs 608 flanking each BPB under test 606. The BPBs under test606, and corresponding sense BPBs 608, are located in respective cornersof the die-attach area 604 and along a diagonal of the die-attach area604. Other embodiments contemplate other arrangements of BPBs under testand corresponding sense BPBs.

FIG. 39 illustrates an active surface 610 of a die. The active surface610 includes BPBs under test 616 and sense BPBs 618. The pattern of theactive surface 610 corresponds to the die-attach area 604 such that whenthe die is flipped to attach to the interposer, BPBs under test 606 andsense BPBs 608 of the interposer align with BPBs under test 616 andsense BPBs 618 of the die, respectively.

FIG. 40 depicts a cross section view of a die 620 having an activesurface 610 as shown in FIG. 39 attached to an interposer 622 having afront side pattern 600 as shown in FIG. 38. The cross section view inthis example is along an outer row or column of the bump structures. Theinterposer 622 has not completed processing in this example but hasproceeded through front side processing and die attach, such asprocessing through FIG. 2D before dispensing underfill. In anotherembodiment, the interposer 622 has proceeded through processing of FIG.3E before dispensing underfill. The structure in FIG. 40 includes BPBsunder test 624, sense BPBs 626, active BPBs 634, probe pads 628 andportions 630 of the top metallization layer of the interposer 622, andportions 632 of the top metallization layer of the die 620. In thisexample, the probe pads 628 are aluminum copper, and the portion 632 isaluminum copper or copper, although other materials previously discussedmay be used.

Referring to FIGS. 38 through 40, each BPB under test 624 (correspondingto 606 and 616 in FIGS. 38 and 39, respectively) has two flanking senseBPBs 626 (corresponding to 608 and 618 in FIGS. 38 and 39,respectively). Each of the bond pads on the interposer 622 for senseBPBs 626 is electrically coupled to a respective probe pad 628. The BPBunder test 624 in this example is electrically coupled to two probe pads628, although only one or more probe pads may be used. In this example,the electrical coupling between the bond pads and the probe pads 628 areby a connection through the top metallization layer, e.g., one of theportions 630 of the third metallization layer 158, but the coupling maybe through various other metallization layers. The bond pads on the die620 for the BPB under test 624 and the sense BPBs 626 are electricallycoupled together through connections by the portions 632 in the topmetallization layer of the die 620, although various combinations ofother metallization layers may be used. In this example, the connectionof the bond pad for the BPB under test 624 to the portion 632 of the topmetallization layer of the die is intermediate the connections of thebond pads for the sense BPBs 626 to the portion 632 of the topmetallization layer.

The structure in FIG. 40 may be tested after attaching the die 620 butbefore, for example, back side processing. The probe pad 628 of one ofthe sense BPBs 626 and one of the probe pads 628 of the BPB under test624 are used to apply a current through the BPB under test 624. Theprobe pad 628 of the other sense BPBs 626 and the other probe pad 628 ofthe BPB under test 624 are used to measure a voltage drop across the BPBunder test 624. Using the applied current and measured voltage drop, theresistance of the BPB under test 624 may be calculated, and whether theBPB under test 624 forms an electrical connection may be determined.

FIGS. 41 and 42 illustrate a modification to the structure in FIGS. 38through 40. FIG. 41 shows a back side pattern 640 of an interposer withthe pattern of the die-attach area 604 of the front side shown inphantom. The back side pattern 640 includes probe pads 642 along aperiphery of the interposer.

FIG. 42 shows a cross section similar to FIG. 40. The structure isprocessed through the die attach step and formation of a back sidemetallization layer, such as after forming a metallization layer in FIG.2F but before forming balls in FIG. 2G. The interposer 644 in FIG. 42includes interconnect structures 646 formed from portions of the first,second, and third metallization layers 154, 156, and 158, respectively,and vias formed therebetween. The interposer 644 further includes TSVs504 between the interconnect structures 646 and portions 648 of a backside metallization layer. The portions 648 electrically couple each TSV504 to a respective probe pad 642. In this example, the probe pads 642are aluminum copper, and the portions 648 are copper, although othermaterials previously discussed may be used.

As with above, each of the bond pads on the interposer 644 for senseBPBs 626 is electrically coupled to a respective probe pad 642, and theBPB under test 624 in this example is electrically coupled to two probepads 642. In this example, the electrical coupling between the bond padsof the interposer 644 and the probe pads 642 are by a connection throughan interconnect structure 646, a TSV 504, and a portion 648 of the backside metallization layer. The bond pads on the die 620 and respectiveconnections are the same as previously discussed with respect to FIG.40.

Similar to FIG. 40, the structure in FIG. 42 may be tested after forminga back side metallization layer but before, for example, the formationof conductive balls. The probe pad 642 of one of the sense BPBs 626 andone of the probe pads 642 of the BPB under test 624 are used to apply acurrent through the BPB under test 624. The probe pad 642 of the othersense BPBs 626 and the other probe pad 642 of the BPB under test 624 areused to measure a voltage drop across the BPB under test 624. Using theapplied current and measured voltage drop, the resistance of the BPBunder test 624 may be calculated, and whether the BPB under test 624forms an electrical connection may be determined.

FIG. 43 is a modification of FIG. 42. Instead of the portions 648 of theback side metallization layer electrically coupling the probe pads 642to the TSVs 504, the portions 648 electrically couple the TSVs 504 toball structures 652, which include ball bond pads, of the back side ofthe interposer 650. In other embodiments, the ball bond pads may bedirectly connected to the TSVs 504 without the presence of a back sidemetallization layer. The testing of the BPB under test 624 may beperformed similarly as discussed with respect to FIG. 42, except theball structures 652 are probed to apply a current and measure a voltageinstead of the probe pads 642.

FIG. 44 is a modification of FIG. 43. The structure in FIG. 44 is thesame as or similar to the structure in FIG. 43 with the addition of asubstrate 660 attached to the interposer 650. The substrate 660 includesball grid array (BGA) ball structures 662. The testing may be performedsimilar to that of FIG. 43, except the BGA ball structures 662 areprobed instead of the ball structures 652 of the interposer 650.

FIGS. 45 through 48 show general concepts of testing the BPB under test624 discussed with respect to FIGS. 38 through 44. FIG. 45 generallycorresponds to the structure in FIG. 40. In testing, a current isapplied through probe pads 628 a and 628 b, and a voltage is sensedthrough probe pads 628 c and 628 d. FIG. 46 generally corresponds to thestructure in FIG. 42. Again, in testing, a current is applied throughprobe pads 642 a and 642 b, and a voltage is sensed through probe pads642 c and 642 d. FIGS. 47 and 48 generally correspond to FIGS. 43 and44, respectively. In testing, a current is applied through ballstructures 652 a and 652 b or BGA ball structures 662 a and 662 b, and avoltage is sensed through ball structures 652 c and 652 d or BGA ballstructures 662 c and 662 d.

FIG. 49 illustrates a method for forming a die attached to an interposerand for testing structures of the interposer and/or die. In step 700, aTSV is formed in an interposer substrate, such as shown in FIG. 2A. Instep 702, a front side RDL is formed, such as in FIG. 2B. In step 704, afirst test or set of tests is performed, such as the general testingdiscussed with regard to FIGS. 20, 21, 27, and 28. It should be notedthat some of these tests may be performed during the formation of thefront side RDL, such as between the formations of various metallizationlayers. In step 706, bump pads and/or bumps are formed on the front sideof the interposer, and a die is attached to the interposer, such asshown in FIGS. 2C and 2D or FIGS. 3D and 3E. In step 708, a second testor set of tests is performed, such as the general testing discussed withregard to FIG. 45.

In step 710, a TSV back side protrusion is formed, and a back sidemetallization may be formed, such as shown in FIG. 2F or 3B. In step712, a third test or set of tests is performed, such as the generaltesting discussed with regard to FIGS. 35, 36, and 46. In step 714, ballpads and balls are formed on the back side of the interposer, such asshown in FIGS. 2G and 3C. In step 716, a fourth test or set of tests isperformed, such as the general testing discussed with regard to FIGS. 37and 47.

In step 718, the interposer and die are diced, such as shown in FIGS. 2Hand 3F. In step 720, a fifth test or set of tests is performed, such asthe general testing discussed with regard to FIGS. 37 and 47. In step722, the diced structures are sampled by performing testing, as is knownin the art. In step 724, a package is assembled by attaching theinterposer to a substrate. In step 726, a yield is determined by methodsknown in the art. In step 728, the test results are correlated to thedetermined yield to identify a processing step that causes defects thatreduces the yield. In step 730, based on the correlation, a process orprocess parameter is refined to increase the yield of the entireprocess.

By using the test structures and testing methods discussed above, knowngood interposers and dies may be more readily identified duringprocessing, which may allow focusing processing on the known goodinterposers/dies. This may increase the cost efficiency of processing,such as by not using time or materials on known defectiveinterposers/dies. Further, by identifying process steps that generatedefects, the process may be refined in a manner that increases theyield.

A first embodiment is a structure comprising an interposer. Theinterposer has a test structure extending along a periphery of theinterposer, and at least a portion of the test structure is in a firstredistribution element. The first redistribution element is on a firstsurface of a substrate of the interposer. The test structure isintermediate and electrically coupled to at least two probe pads.

Another embodiment is a structure comprising an interposer, a die,conductive bumps, a test structure, and at least two electricalterminations. The conductive bumps electrically couple the die to theinterposer. The test structure comprises at least one of the conductivebumps. The at least two electrical terminations are on the interposer,and the test structure is intermediate and electrically coupled to theat least two electrical terminations

A further embodiment is a method comprising forming a dummy teststructure, the dummy test structure being at least partially in aninterposer; applying a test signal to the dummy test structure; andsensing a response of the dummy test structure to the test signal.

Although the present embodiments and their advantages have beendescribed in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims. Moreover, the scope of the present application is not intendedto be limited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present disclosure.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A structure comprising: an interposer having atest structure extending along a periphery of the interposer, at least aportion of the test structure being in a first redistribution element,the first redistribution element being on a first surface of a substrateof the interposer, the test structure being intermediate andelectrically coupled to at least two probe pads.
 2. The structure ofclaim 1, wherein the test structure comprises a portion of a seal ringin a metallization layer of the first redistribution element, the probepads being in the metallization layer.
 3. The structure of claim 1,wherein the test structure comprises a portion of a seal ring in ametallization layer of the first redistribution element, the probe padsbeing over the metallization layer.
 4. The structure of claim 1, whereinthe test structure comprises a first portion of a seal ring in a firstmetallization layer, a second portion of the seal ring in a secondmetallization layer, and a third portion of the seal ring in a thirdmetallization layer, the second metallization layer being over the firstmetallization layer, the third metallization layer being over the secondmetallization layer, the first portion being intermediate andelectrically coupling first at least two probe pads, the second portionbeing intermediate and electrically coupling second at least two probepads, the third portion being intermediate and electrically couplingthird at least two probe pads, the first, second, and third at least twoprobe pads being over the third metallization layer.
 5. The structure ofclaim 1, wherein the test structure comprises a conductive line betweena first seal ring and a second seal ring, the conductive line being in ametallization layer of the first redistribution element, the probe padsbeing in the metallization layer.
 6. The structure of claim 1, whereinthe test structure comprises a conductive line between a first seal ringand a second seal ring, the conductive line being in a metallizationlayer of the first redistribution element, the probe pads being over themetallization layer.
 7. The structure of claim 1, wherein the teststructure comprises a first conductive line, a second conductive line,and a third conductive line, the first conductive line, the secondconductive line, and the third conductive line each being between afirst seal ring and a second seal ring, the first conductive line beingin a first metallization layer, the second conductive line being in asecond metallization layer, and the third conductive line being in athird metallization layer, the second metallization layer being over thefirst metallization layer, the third metallization layer being over thesecond metallization layer, the first conductive line being intermediateand electrically coupling first at least two probe pads, the secondconductive line being intermediate and electrically coupling second atleast two probe pads, the third conductive line being intermediate andelectrically coupling third at least two probe pads, the first, second,and third at least two probe pads being over the third metallizationlayer.
 8. The structure of claim 1, wherein the test structure comprisesa via chain between metallization layers of the first redistributionelement, the probe pads being over the metallization layers.
 9. Thestructure of claim 8, wherein the metallization layers comprise a firstmetallization layer, a second metallization layer, and a thirdmetallization layer, the via chain comprising first vias and secondvias, the first vias being between the first metallization layer and thesecond metallization layer, the second vias being between the secondmetallization layer and the third metallization layer, at least one ofthe first vias not being vertically aligned with at least acorresponding one of the second vias.
 10. The structure of claim 8,wherein the metallization layers comprise a first metallization layer, asecond metallization layer, and a third metallization layer, the viachain comprising first vias and second vias, the first vias beingbetween the first metallization layer and the second metallizationlayer, the second vias being between the second metallization layer andthe third metallization layer, each of the first vias being verticallyaligned with at least a corresponding one of the second vias.
 11. Thestructure of claim 8, wherein the via chain is at least partially in anisolation area interior to a seal ring of the interposer.
 12. Thestructure of claim 1, wherein the test structure comprises a pluralityof through substrate vias (TSVs), the plurality of TSVs extending fromthe first surface of the substrate to a second surface of the substrate,the plurality of TSVs being electrically coupled together serially bythe first redistribution element and by a second redistribution elementon the second surface of the substrate.
 13. A structure comprising: asubstrate having a plurality of metallization layers in respective onesof a plurality of dielectric layers on a first surface of the substrate,the substrate further comprising a through via extending from the firstsurface of the substrate, a first probe pad being on or in the pluralityof dielectric layers proximate a first corner of the substrate, a secondprobe pad being on or in the plurality of dielectric layers proximate asecond corner of the substrate, a test structure in the plurality ofmetallization layers being electrically coupled between the first probepad and the second probe pad and physically extending along a peripheryof the substrate.
 14. The structure of claim 13, wherein the teststructure comprises a line in one of the plurality of metallizationlayers.
 15. The structure of claim 13, wherein the test structure is aportion of a seal ring.
 16. The structure of claim 13, wherein the teststructure is disposed between an inner seal ring and an outer seal ring.17. The structure of claim 13, wherein the test structure comprises avia chain through the plurality of dielectric layers.
 18. A structurecomprising: an interposer comprising: a substrate having a throughsubstrate via, and a redistribution element on the substrate, theredistribution element comprising metallization layers in respectiveones of dielectric layers, a seal ring being in the redistributionelement and comprising portions of the metallization layers, the sealring being along a periphery of the substrate, a first probe pad beingat a first corner of the substrate and on or in the redistributionelement, a second probe pad being at a second corner of the substrateand on or in the redistribution element, a test structure beingelectrically coupled between the first probe pad and the second probepad and extending physically along the seal ring, the test structurecomprising a portion of the metallization layers in the redistributionelement.
 19. The structure of claim 18, wherein the test structurecomprises a metal line in one of the metallization layers.
 20. Thestructure of claim 18, wherein the test structure comprises a via chain.